Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$246.62	9.266%	$269.4718	$269.47	$269.45	$269.50
Purchase #2	$124.42	6.188%	$132.1191	$132.12	$132.10	$132.10
Purchase #3	$14.40	5.608%	$15.2076	$15.21	$15.20	$15.20
Purchase #4	$135.86	12.541%	$152.8982	$152.90	$152.90	$152.90
Purchase #5	$240.46	10.873%	$266.6052	$266.61	$266.60	$266.60
Purchase #6	$90.81	10.733%	$100.5566	$100.56	$100.55	$100.60
Purchase #7	$73.34	12.105%	$82.2178	$82.22	$82.20	$82.20
7 purchase totals =	$925.91		$1,019.0763	$1,019.09	$1,019.00	$1,019.10